Teeth from urine could become a new reality, as Chinese researchers have managed to take the stem cells found in human waste and repurpose them to grow teeth. Although some call the current methods impractical, scientists point out that its far easier than the current method- taking stem cells from a small chunk of skin.

Making teeth from urine was the mission of Duanqing Pei, a professor of stem cell biology at the Guangzhou Institutes of Biomedicine and Health. He and a team of researchers managed to convert epithelial cells found in urine to induced pluripotent cells- iPS cells for short- and put them in special conditions to form hard teeth.

"We have a long-running interest in tooth formation," Pei told ABC News. "We want to use somebody's own cells to generate a tooth," as opposed to foreign cells, which could be rejected by a body's immune system.

In order for the iPS cells to take on the qualities necessary to form teeth, the researchers implanted it in a mouse's kidney along with tissue from the mouse's jaw. The human cells became ameloblasts and began to secrete enamel, which is the hard substance found on the outside of teeth. Three weeks later, the team was able to remove a hybrid mouse-human tooth with the same hardness "found in the regular human tooth," according to their study published in journal Cell Regeneration.

"The primitive teeth-like organs are structurally and physically similar to human teeth," Dr. Pei said. "They are of roughly the same elasticity, and contain pulp, dentin and enamel-forming cells."

Still, there are setbacks that still need to be overcome with the method.

"The method has its limitations- it involves mouse cells, has a success rate of around 30 percent and the structures were about one-third of the hardness of human teeth," he admitted.

Other scientists, like Professor Chris Mason of University College London, criticized the study for its lack of efficiency, saying urine is "probably one of the worst sources" for stem cells.

"There are very few cells [in urine] in the first place and the efficiency of turning them into stem cells is very low," Mason told BBC. "You just wouldn't do it this way."

However, another scientist pointed out that the best way for getting stem cells from children- a biopsy, which requires a 1-centimeter square to be taken from the skin- may not always be preferable for parents. Taking stem cells from urine could solve that problem.

"Doctors are looking for noninvasive ways to get cells from children," Sean Morrison, director of the Children's Research Institute of the University of Texas-Southwestern Medical Center, told ABC. "This could represent a better way of getting a child's stem cells."